Find
out how
wind power can be stored and sold at times of peak demand

Wind
power suffers from one major problem
- the wind
is very fickle. Ifwind
turbinesare to be a viable
large scale replacement for coal- and gas-fired power stations, a way has to be
found to capture and store the energy from the wind so that it can be put to
use when it is needed, and not just when the wind is blowing. Sinceelectricityfrom wind turbines is more
expensive than that generated by conventional power stations, another benefit
of storing wind power is that electricity can be exported to the National Grid
at peak times of day when the price paid for it can be 2 or 3 times greater
that at off peak times. This makes wind turbine generators financially viable
without the need for government subsidies.

Compressed Air
Storage

One
possible
solution to this energy storage problem is the use ofcompressed air. When the
wind blows during the night (when electricity demand is low), the electricity
generated can be used to power anair
compressor. The compressed air can then be stored in the underground caves
and caverns left from some forms of mining. During the day when demand peaks
(and wholesale electricity prices peak) the compressed air can be released
through a turbine generating electricity. These caverns will effectively
providebattery storagefor wind
power.

The
overallefficiencyof this system can be as
much as75%. Although 25%+ of the wind
generated electricity is lost, the remaining 75% is used at peak times thus
reducing the number of conventional power stations needed to meet demand.

Although
acompressed air energy storage(CAES) system has not been tested commercially
withwind turbines, a
290MW plant in Huntdorf, Germany has been running
successfully for over25 yearsstoring excess
production from a
conventional power station so it can be sold at times ofpeak demand.
Compressed air is
stored in engineered salt caverns, and when released can generated sufficient
electricity to meet the needs of almost 300,000 homes. A second commericial
unit was built in 1991 in McIntosh, Alabama
with a110MWturbine.

Other
(conventional) sources of electricity could be stored in the same way further
reducing the number of conventionalpower
stationsrequired to meet
peak demand is reduced.The
Future for CAES and Wind PowerAs
morewind farmsare constructed,
and our dependence
on the electricity they generate increases,energy
storageis going to become
more and more important. InNorth

Dakota, the windiest state of the USA,Sirius Exploration plan to create eight
16m (diameter) x 160m caverns (bypotashmining) which will be able to
power a100MWturbine when
filled with
compressed air. A similar projet is being developed in Ireland byGaelectric with
a cavern large
enough for at least a136MWturbine.

Pumped
Hydro - An Alternative Technology

The other main alternative to compressed air energy storage is pumped
hydro - a very well established technology in which electricity
generated at times of low demand is used to pump water from a low lake to a
high lake. At times of peak electricity demand the water in the upper lake is
released down through a turbine. Pictured above is the Sloy Power
Station which uses pumped hydro technology (and was constructed many
decades ago